Electrical system of distribution.



A. S. HUBBARD.

ELECTRICAL SYSTEM OF DISTRIBUTION.

APPLICATION FILED FEB. 10. I909.

1, 1 34,837. Patented Apr. 6, 1915.

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A. S. HUBBARD.

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UNITED STATES PATENT OFFICE.

ALBERT S. HUBBARD, 0F BELLEVILLE, NEW JERSEY, ASSIGNOR TO GOULD STORAGEBATTERY COMPANY, A CORPORATION OF NEW YORK.

ELECTRICAL SYSTEM OF DISTRIBUTION.

Specification of Letters Patent.

Patented Apr. 6, 1915.

Application filed February 10, 1909. Serial N 0. 477,222.

To all whom it may concern:

Be it known that I, ALBERT S. HUBBARD, a citizen of the United States,and a resident of Belleville, county of Essex, and State of New Jersey,have invented certain new and useful Improvements in Electrical Systemsof Distribution, of which the following is a specification.

My invention relates to improvements in electrical systems ofdistribution and especially to systems in which a compensatory batteryis connected at a station or substation and regulated by a booster tosteady the load upon the main dynamo.

The object of my invention is to automatically limit the current that ispermitted to fall upon the battery and booster and to automatically varythe station potential when the battery current is limited, so that theactual load on the booster may be still further reduced and that on themain generator or sub-station converting apparatus may also be limitedwhen desirable. I achieve this object by a means automaticallycontrolled by battery current or booster voltage or both and acting toreduce or oppose the usual automatic regulation of the booster, and bymeans similarly controlled and acting to vary the field-strength of themain dynamo or motor generator or rotary converter of the station orsub-station and so the line potential.

By my invention I am enabled to provide batteries, boosters, andregulating apparatus of relatively small size and so comparativelycheap, while moreover the source of current at the station orsub-station may supply a substantially constant load, notwithstandingthe increased current such source is called upon to supply when thedischarge of the battery has become limited. The source, therefore, neednot be enlarged by reason of the limiting of battery load, and, wherethe invention is embodied in a sub-station, the electric energy suppliedthereto may be maintained substantially uniform.

My invention also includes the same limitation, if desired, of batterycurrent and booster load when the battery is charging at a high rate,the potential of the station in this instance being increased at suchtime.

Further objects, advantages and features will more clearly appear fromthe detailed description given below, taken in connection with theaccompanying drawings, which form a part of this specification.

In the drawings Figure 1 shows diagrammati cally a system embodying oneform of my nvention. Fig. 2 represents diagrammatically and in detailportions of the regulating apparatus and circuits used in the systemshown in Fig. 1 with some additional features. Fig. 3 is a view similarto Fig. 2 but showing a modified form of regulating apparatus.

Referring to Fig. 1, 1 represents a main generator supplying the feedcircuit 2, 2 which is connected with its load 3, which may consist oflamps or other translating devices. The main generator 1 may be in theform of a converter supplied by the alternating current circuit 1 or inthe form of motor generator apparatus, or may be a dynamo driven fromany usual source of power. As shown it is provided with shunt fields 4.Connected across the feed circuit 2, 2, is a battery circuit 5, 5 withthe battery 6 in series therein, and in series with the battery is abooster 7 driven by a shunt motor 8 connected across the circuit 2, 2 byconductors 9. The booster 7 is excited by field coil 10 connected inseries with the armature of an exciter 11. The exciter 11 is providedwith a field coil 12 connected in a circuit 13, 13 across the maincircuit 2, 2 and having in series therewith the armature of a countermachine 14:. Both the exciter 11 and counter machine 143 are driven by ashunt motor 15 connected across the main circuit 2, 2 by conductors 16.The counter machine 14 is primarily excited by field coil 17 connectedin shunt to a resistance 18 in series in the main circuit 2, 2. Theresistance 18 may be varied by means of a movable contact 44:.

IVhen the load on the system is normal and the battery is floatingacross the line the field strength of coil 17 is just sufiicient tocause the counter machine 14 to produce an electro-motive-force exactlyequal, but in the opposite direction to the electro-motive-force appliedto the circuit 13, 13 from the main feed circuit 2, 2. If the load onthe system increases the strength of windings 17 increases, therebyincreasing the potential produced by the contour machine 11 so that acurrent is produced in the circuit 13 and the field coil 12 of exciter11 is energized in such a direction as to cause the exciter 11 toenergize the field coil 10 of thebooster- 7 to cause the booster toproduce a voltage in a direction to cause the battery to discharge andtake substantially the additional load placed upon the system. If theload on the system drops below normal the coil 17 is weakened and thevoltage of the line overcomes the opposing voltage of the countermachine 14, whereby the exciter 11 produces a current in the oppositedirection to oppositely excite the booster 7 so that it produces avoltage in a direction to cause the battery to be charged from the mainfeed circuit 2, 2 and thereby tend to maintain the load on the generator1 constant. In such systems it is often found desirable to limit theload which may thus be placed upon the battery both when the battery ischarging and discharging. In order to accomplish this I provide thecounter machine 1 1 with a field coil 19 in series in a circuit 45 andso that it is connected to be responsive to fluctuations of current inthe battery circuit and to fluctuations of booster voltage. The coil 19is connected at one end to the movable member 20 of the variableresistance arrangement 21, one end of the variable resistance 21 beingconnected to a conductor 22 of an auxiliary supply circuit. The otherterminal of the field coil 19 is connected to the other conductor 23 ofsaid supply circuit. By moving the arm 20 the resistance 21 is variedthereby varying the current in field coil 19. WVhen the arm 20 is movedto its lowermost position so that all of the resistance 21 is placed incircuit, the resistance 21 is so large that the current in field coil 19will be inappreciable.

The booster 7 is provided with two commutators 24: and 25 connected inparallel in the battery circuit. The auxiliary feed circuit 22, 23 isconnected to be supplied from the voltage developed across the booster7, as shown.

26 and 27 are two motors or dynamometers having their armaturesconnected in series across the circuit 22, 23 with a high temperaturecoefiicient resistance 28 in series therewith to limit the currenttherethrough. The field 29 of motor 26 is also connected across thecircuit 22, 23 and is therefor responsive to variations in the boostervoltage. The field 30 of the motor 27 is connected in series in acircuit 31 which is connected across a shunt 32 in series with thebattery circuit, so that the coil 30 is responsive to changes of currentthrough the booster and battery. The motors or dynamometers 26 and 27are provided with mechanical apparatus so that they will not operateuntil the field coils 29 or 30 have reached a predetermined excitation,and this predetermined excitation may be different in the case of eachmotor. The apparatus is further arranged so that each motor will valueof current in the field coil 30 corresponding to current in the battercircuit, or a predetermined'current in the eld coil 29 corresponding toa predetermined value of booster voltage, either one or the other of thedynamometers 26 or 27 operate to cause the movable arm 20 to decreasethe variable resistance 21 and thereby increase the excitation of fieldcoil 19 in such a direction as to oppose the action of field coil 17 ofthe counter machine and thereby counteract its regulating functions sothat the generator 1 is caused to take further increases of load and theload on the battery and its circuit is limited.

It will be apparent, that with increases of load on the battery circuitthe voltage across the booster increases correspondingly and it is oftendesirable to limit the voltage which Will be applied to the booster,especially if the design of the booster is such that it will take only adefinite load and will not warrant the passage of large currentstherethrough at such high voltages. In order to bring about theseadvantages and limit the load which will be applied to the booster, Iprovide means for cutting down the voltage of the feed circuit 2, 2thereby decreasing the difference in voltage between the battery and thefeed or consumption circuit 2, 2 so that the voltage across the booster7 is thereby decreased. I effect this action responsively to variationsfrom a predetermined value of battery current and from a predeterminedvalue of booster voltage, by varying the field strength of the maingenerator, thereby varying its voltage which is applied to theconsumption of feed circuit 2, 2.

The voltage of the main generator 1 is varied by the application theretoof an auxiliary field 34: connected in series in a circuit 35 across theauxiliary supply conductors 22, 23. The field 3 1 has in seriestherewith a variable resistance 36 operated by a movable arm 37, whichin turn is controlled by dynamometers 38 and 39 in the same manner asdynamometers 26 and 27. The dynamometers 38 and 39 have their armaturesconnected in series in a circuit 40 connected across the auxiliarysupply mains 22, 23 with a high temperature co-efiicient resistance 41in series therewith in order to limit the current therethrough. Thedynamometer 38 is made responsive in its action to variations in thevoltage of the booster by having its field coil 42 connected across theauxiliary supply circuit 22, 23, which is fed by the booster voltage.The dynamometer or motor 39 is made responsive in its action to thebooster current or current in the battery circuit by having its fieldcoil 43 connected in series in the circuit 31 which is connected acrossthe shunt 32 in the battery circuit. The dynamometers or motors 38 and39 are also provided with means for rendering them inoperative until thecurrents in the coils 42 and 43 shall have reached a predetermined valueso that the voltage of the feed circuit 2, 2, is not decreased until theload on the booster has reached a predetermined value.

The dynamometers 38 and 39 are brought into action to decrease the lineof voltage, so that so much energy will not be lost in the booster andin the booster motor when the booster is carrying heavy loads. The timewhen the dynamometers 38 and 39 are brought into operation is purely amatter of design and the dynamometers 38 and 39 may be brought intooperation at any desired point in the operation of the system accordingto the particular requirements of the system to which my invention isapplied.

Referring to Fig. 2, I there show regulating apparatus for controllingthe coils l9 and 34 as above described. The various dynamometers 26, 27,38 and 39 are connected as shown in Fig. 1. The movable arm 20 isconnected to rotate about the point 46. The dynamometer 26 drives apinion 47 which meshes with a pinion 48 carrying a pin 49 which when themotor 26 rotates causes the pin 49 to rotate so that it moves the arm 20over the various contact points of the resistance 21. A spring 50 actsto tend to return the arm 20 back to its original position against astop 51. The motor 27 is connected to drive a pinion 52 which mesheswith a pinion 53 which carries a stop 54 adapted to engage the arm 20when the pinion 53 rotates and move the arm over the various contactpoints of the resistance 21. It will thus be seen that each motor orboth together must generate a torque sufiicient to overcome the opposingaction of the spring 50 before the arm 20 will be rotated, and it willbe further apparent that each motor or dynamometer may act independentlyof the other and that one motor may have developed a torque suflicientto move the arm 20 without the other one having done so, so that the arm20 moves responsively to the motor generating the greatest torque. Theaction of the motors may be further varied by means of springs 55 and 56upon the shafts of the motors 26 and 27, respectively. These springs areconnected at one end to the frame of the machine and at the other end tomembers 57 and 58, which are secured to the shafts of the respectivemachines. The tension of these springs 55 and 56 may be independentlyadjusted so that the torques which the motors must produce beforeovercoming the opposing actions of these springs may be quite different.When the dynamometers are at rest the members 57 and 58 contact with thestops 59 and 60 being forced thereagainst by the springs 55 and 56. Itwill thus be apparent that each motor or both motors will have toproduce a torque sufficient to overcome the opposing action of itsspring 55 or 56 and the spring 50 before any turning movement will beimparted to the arm 20. By adjusting the tension of these springs eachmotor may be made to produce a different torque before it will cause anymovement of the arm 20.

The motors 38 and 39 are provided with similar appurtenant apparatus tothat shown in connection with motors 26 and 27. Thus the motor 38 drivesgear 61 meshing with gear 62, which carries a pin 63 for moving the arm37. Motor 39 carries a gear 64 meshing with gear 65 which carries a pin66 for moving the arm 37 over the contacts of the variable resistance36. These motors are also provided with adjusting springs 67 and 68.Since the various field coils 29, 30, 1

42, 43 of the various motors are connected across the terminals of thebooster or in shunt to the battery circuit, the current in these coilswill vary in direction in accordance with the direction of the currentin the battery circuit. In order that the value of the field excitationof these motors may be regulated differently when the current in thebattery circuit is in one direction from the regulation when the currentof the battery circuit is in the other direction, I provide field coils69 on each of the motors 26, 27, 38 and 39, which field coils areconnected to a circuit 70, 7 O, which is connected to any convenientsource of electro-motive-force,

such as the circuit 2, 2. High temperature co-efficient resistances 71may be placed in series with each of these field coils 69 in order tomaintain the current therein substantially constant.

From the above it will be apparent that the various dynamometers shownin Fig. 2 are rendered inoperative until the currents in theirrespective field coils 29, 30, 42 and 43 have reached a predeterminedvalue, if no auxiliary excitation is provided. Therefore the presence offield coil 69 causes the value of excitation due to field coils 29, 30,42 and 43 to be increased when the battery current is in one directionand to be decreased when the battery current is in the other direction.It will, therefore, be clear that the dynamometers act upon variationsfrom a predetermined electrical condition of the booster when thebattery current is in one direction, and act upon the variations from adifierent and independent predetermined electrical condition of thebooster when the battery current is in the opposite direction.

Referring to Fig. 3, I show the dynamometer regulating apparatus similarto that shown in Fig. 2, but with the elimination of the field coil 69and with the substitution of mechanical apparatus for effectingsubstantially the same result. The variable resistance 21 is connectedin series in circuits 45, 45 which is connected to the field 19 of thecounter-electro-motive-force machine 14. The variable resistance 36 isconnected in series in the circuit 35, 35 which leads to the auxiliaryfield winding 34 on the main generator 1. In both Figs. 2 and 3 I haveshown this circuit 35 connected to several knife switches so thatvarious parts of the field 34 or other auxiliary fields may be thrown incircuit upon the generator. The field coils 30 and 43 on the motors 27and 39, respectively, are connected across the circuit 31, which isconnected across the shunt 32 in the battery circuit. The field coils 29and 42 of the motors 26 and 38, respectively, are connected to theauxiliary field circuit conductors 22 and 23 which are in turn connectedacross the booster potential. In this figure, therefore, instead ofconnecting the various armatures across the booster potential I haveshown an arrangement whereby they maybe connected across some othersource of electro-motive-force by means of knife switch 72. This sourceof potential may be, if desired, the circuit 2, 2.

The variable resistance 21 is controlled by means of two contact arms 73and 74. The shaft of motor 26 is connected to drive a pinion 75 whichmeshes with a pinion 76, which pinion carries a projection 77 adapted toengage and move either of the arms 73 or 7 4 in accordance with thedirection in which the pinion 76 rotates. The motor 27 is connected todrive a pinion 78 meshing with gear 79 which has secured thereto aprojection 80 adapted to engage with either of the extensions 81 or 82of the arms 73 and 74, respectively, to rotate either one or the otherof them in accordance with the direction of rotation of the pinion 79.Thus when the field strength of coil 29 has reached a predeterminedvalue in one direction the arm 73 is moved over the various contacts ofresistance 21 and when the motor 26 has reached a predeterminedexcitation in the other direction the arm 74 is moved over the variouscontacts of resistance 21. In a similar manner the motor 30 operateseither one or the other of the arms 73 or7 4 in accordance with thedirection of its field excitation. arms 73 and 74 are acted upon bysprings 83 and 84, respectively, to bring them back to their normalpositions against stops 85 and 86 when the motors 26 and 27 are renderedinoperative. The motor 26 is provided with shaft 87 carrying gear 88which meshes with the gear 89, which in turn is connected to a shaft 90.The shaft 90 is provided with arms 91 and 92 at either of its ends.

93 and 94 are shafts carrying arms 95 and 96, respectively, withextensions 97 and 98, which extensions are held against stops 99 and 100by means of coil springs 101 and 102 secured to the frame at one end andto the shafts 93 and 94, respectively, at their other end. By adjustingthe tension of the springs 101 and 102 to difierent values the torquenecessary to cause the shaft 87 to turn in one direction may be madedifierent and independent from the torque necessary to cause the shaft87 to turn in the other direction. That is, when turning in onedirection a torque must be applied to the shaft 87 sufiicient toovercome the initial tension ofspring 101 before the shaft will begin toturn, and when the torque is applied in the other direction it must besulficient to overcome the tension of spring 102 before the shaft willbegin to turn. In this manner the predetermined value at which the motor26 operates responsively to voltage variations of the booster is variedin accordance with the direction of the current therethrough. V In asimilar manner the action of dynamometer 27 may be varied so that thepredetermined value at which it will operate will be diiferent when thebattery current is in one direction from the predetermined value atwhich it will operate when the batterycurrent is in the other direction.Since the parts for causing this operation are exactly similar to thosefor causing the similar operation of the motor 26, a detaileddescription thereof'need not be given.

The motors or dynamometers 38 and 39 are controlled mechanically toadjust the predetermined values of booster voltage and current ondepartures from which they op erate in exactly the same manner as themotors 26 and 27 and therefore a detailed de scription thereof is notnecessary.

Although in Fig. 2 I have shown an ar-.

rangement whereby the pair of dynamometers which operate upon theregulating field coil 19 is the same as the pair of dynamometers whichoperate upon the regulating field coil 34, and in Fig 3 I have shown thepair ofdynamometers which operate upon the field coil 34 the same as thepair of dynamometers which operate upon the field coil 19, nevertheless,it will be apparent that the arrangement of dynamometers shown in Fig. 2might be used to control the field coil 19, while a pair of dynamometerssuch as is The shown in Fig. 3 could be used to control the field coil34, or vice versa, or any one of the motors or dynamometers 26, 27, 38or 39 and its appurtenant mechanical and electrical mechanism might besubstituted for any one of the others, and I desire it to be understoodthat I fully comprehend such changes and improvements in my invention.

Referring to Fig. 1, the general operation of the system is as follows.Then the load on the system is at the predetermined average value thecounter-machine furnishes no current and the booster is not excited. Thebooster, therefore, produces no voltage and the battery will floatacross the line. When the load on the system increases the booster isexcited in a direction to cause the battery to discharge and take theincrease in load. This action occurs up to a certain point when thebooster voltage or the battery current becomes suflicient to excitedynamometer 26 or 27, so that variable resistance 21 is operated,thereby preventing a further increase in the excitation of thecounter-machine or causing a decrease in the excitation of thecounter-machine and preventing a further increase in the booster voltageor causing a slight decrease in booster voltage so that the generatorwill take all further increases in load on the system. In a similarmanner, if the load on the system decreases below the average value thebattery will receive a charging current up to a certain value, whichvalue is determined by dynamometer 27. If the current through thebattery tends to become greater than this value the dynamometer 27 soaifects the booster voltage that the battery current is decreased orprevented from increasing. In a like manner the battery charging currentmay be determined by the dynamometer 26, in accordance with the boostervoltage. It is to be noted that the field 19 being connected across thebooster has a direction of current depending upon the direction ofcurrent through the booster. When, therefore, the booster is dischargingthe current in field 19 is in one direction and when it is charging isin the opposite direction. The current in field 19, therefore, alwaystends to cut down the electromotive force applied to the coil 12 of theexciter 11 and therefore the current in the booster field 10. Therefore,an increase of current in coil 19 either on charge or discharge, tendsto reduce the booster voltage and so the current in the battery circuit.

When the load on the system increases above its average value and whenthis increase in load becomes very heavy the load upon the motor 8 andthe energy absorbed by the booster 7 becomes quite large. To decreasethe energy thus lost the voltage of the main generator is decreased,thus decreasing the line voltage so that the voltage of the boostercircuit has to be raised only very slightly, if at all, in order todischarge the proper energy onto the line. This action is affected bymeans of the dynamometers 88 and 39 responsive to the booster voltageand battery current respectively, so that when these factors becomefairly large the line voltage is decreased, thereby decreasing the lossof energy in the booster motor 8 and booster 7. In actual practice it isfound that this can be done without materially altering the load on themain generator 1 and it is immaterial which of the sets of dynamometers26 and 27 or 38 and 39 operate first. In a like manner when the batteryis charging, if the energy absorbed by the motor 8 and booster 7 shouldbecome excessive, the voltage of the main generator may be increased tocut down this loss without materially affecting the output of the maingenerator. The field winding 34 of the source 1 being connected acrossthe booster has a current whose direction depends upon the direction ofcurrent through the booster and it is for this reason that, as abovedescribed, the line voltage is decreased when the dynamometers 38 and 39are operated on the discharge of the battery to reduce resistance 36 andis increased when the same dynamometes act to decrease this resistanceand the battery is charging.

From the above it will be clear that I have provided an exceptionallyefficient and effective means for regulating and adjusting the potentialof the main generator 1 and regulating the potential applied to thebooster 7 so that the electrical condition thereof is limited so thatdamage will not be done thereto and excessive loads placed thereupon. Itwill also be apparent that by providing the auxiliary supply circuit 22,23 connected across the booster terminals I eliminate a wasteful use ofenergy since when it is not desired to utilize the dynamometers forregulating purposes the energy of the circuits 22, 23, which suppliesthe dynamometers is much decreased, and if the battery is floating thisenergy may be 1127.

Althrough I have described my improvements in great detail and withreference to a specific system, it is evident that my broad invention isapplicable to many other kinds of systems and arrangements, but

Having described my improvements fully and clearly, what I claim anddesire to se cure by Letters Patent is:

1. The combination of a source of electricity, a storage battery inparallel therewith, a booster regulated to compel the battery todischarge to compensate for increases of load, and means, maintainedinoperative during the discharge of the battery until a given. batterycurrent is reached, for reducing the potential of said source.

2. The combination of a source of electricity, a storage battery inparallel therewith, a booster regulated to compel the battery todischarge to compensate for increases of load, and means, maintainedinoperative during the discharge of the battery until a given boosterpotential is reached, for re ducing the potential of said source.

3. The combination of a source of electricity, a storage battery inparallel therewith, a booster regulated to compel the battery todischarge to compensate for increases of load, and means, maintainedinoperative during the charge of the battery until a given batterycurrent is reached, for increasing the potential of said source.

4. The combination of a source of electricity, a storage battery inparallel therewith, a booster regulated to compel the battery todischarge to compensate for increases of load, and means, maintainedinoperative during the charge of the battery until a given boosterpotential is reached for increasing the potential of said source. 7 5.The combination of dynamo apparatus receiving alternating current andsupplying direct current, a storage battery in parallel with the directcurrent supply mains thereof, means for limiting the battery load, andmeans operating independently of said limiting means for decreasing thedirect current potential from said dynamo apparatus.

6. The combination of dynamo apparatus receiving alternating current andsupplying direct current, a storage battery in parallel with the directcurrent supply mains thereof, a booster in series with the battery andregulated to compel the discharge of the battery, means for limiting thebooster potential, and means operating independently of said limitingmeans for decreasing the direct current potential from said dynamoapparatus.

7. The combination of a dynamo source of electricity, a compensatorystorage battery, a booster for controlling the charge and discharge ofthe battery, means for limiting the battery current, motor apparatusgoverning a resistance in a field winding of said source, said motorapparatus being connected to be operated through a current varying withthat of said battery, and means opposing the operation of said motorapparatus.

8. The combination of a dynamo source of electricity, a compensatorystorage battery, a booster for controlling the charge and discharge ofthe battery, means for limiting the booster potential, motor apparatusgoverning a resistance in a field winding of said source, said motorapparatus being connected to be operated through a current varying withthe potential of said booster, and means opposing the operation of saidmotor apparatus.

9. The combination of a dynamo source of electricity, a compensatorystorage battery, a booster for controlling the charge and discharge ofthe battery, means for limiting the booster potential, motor apparatusgoverning a resistance in a field winding of said source, said motorapparatus being connected to be operated through a current varying withthat of said battery and also through a current varying with the boosterpotential, and means opposing the operation of said motor apparatus.

10. In an electrical system of distribution,

'a generating source of el ctric current, a

battery and its circuit connected thereto, a booster in series with thebattery, and means for regulating the voltage of said source responsiveboth to voltagle variations of the booster and current fluctuations ofthe booster circuit.

11. In an electrical system of distribution, a source of current, acircuit and its load connected thereto, a storage battery and itscircuit and booster in operative relation thereto, means including thebooster for controlling the division of load between the generator andbattery, a device provided with a coil responsive to changes in theelectrical condition of the booster, means acted upon by said device forcontrolling the voltage across the source, and means for rendering saiddevice inactive until the current in said coil has reached apredetermined value.

12. In an electrical system of distribution, a source of current, acircuit and its load connected thereto, a storage battery and itscircuit and booster in operative relation thereto, means including thebooster for controlling the division of load between the generator andbattery, apparatus pro vided with windings responsive to current andvoltage changes in the booster, means acted upon by said apparatus forcontrolling the voltage of said source and thereby the load on thebooster, and means for rendering said apparatus inoperative until thecurrent in said windings has reached a predetermined value.

13. In an electrical system of distribution, a main source of electricalenergy, a feed circuit and its load supplied thereby, a storage batteryand its circuit in operative relation thereto, a booster for controllingthe battery action, means responsive to load changes on the system forregulating the booster, means for counteracting said regulating meansresponsive to changes in the electrical condition of the batterycircuit, and independent means for varying the voltage of the feedingcircuit to limit the load on the booster responsive to variations in theelectrical condition thereof.

14. In an electrical system of distribution, a source of electricenergy, a feed circuit and its load supplied thereby, a storage batteryand its circuit in operative relation thereto, a booster for controllingthe action of the battery, a device for varying the voltage of thefeeding circuit, a coil for controlling the action of said deviceresponsive to fluctuations of current in the battery circuit, and meansfor rendering said device inoper ative until the current in said coilhas reached a predetermined value.

15. In an electrical system of distribution, a source of electricenergy, a feed circuit and its load supplied thereby, a storage batteryand its circuit in operative relation thereto, a booster for controllingthe action of the battery, a device for varying the voltage produced bysaid source to limit the load on the booster, a coil for controlling theaction of said device responsive to voltage fluctuations of the boosterand means for rendering said device inoperative until the potentialacross the terminals of the booster has reached a predetermined value.

16. In an electrical system of distribution, a generating source ofelectric energy, a feed circuit and its load supplied thereby, a storagebattery and its circuit in operative relation thereto, a booster forcontrolling the action of the battery, a device for varying the voltageproduced by said source to limit the load on the booster, a coil forcontrolling the action of said device responsive to changes in theelectrical condition of the battery circuit, and means for renderingsaid coil operative when the battery circuit has reached a predeterminedcondition when the battery is discharging, and for rendering said coiloperative when the battery circuit has reached a different conditionwhen the battery is charging.

17. In an electrical system of distribution, a generating source ofelectric energy, a feed circuit and its load supplied thereby, a storagebattery and its circuit in operative relation thereto, a booster forcontrolling the action of the battery, apparatus for varying the voltageproduced by said source to limit the load on the booster, means forcontrolling said apparatus responsive both to fluctuations of boostercurrent and booster voltage, and means for controlling said apparatus tocause it to operate only when the booster current has reached apredetermined value or only when the booster voltage has reachedpredetermined value.

18. In an electrical system of distribution, a source of electriccurrent, a feed circuit and its load supplied thereby, a battery and itscircuit in operative relation thereto, a booster for controlling thebattery action, and means for varying the potential of said source tocontrol the load on the booster responsive to departures from apredetermined electrical condition of the booster, said means includinga motor arrangement connected to have a substantially constant armaturecurrent when it is operative and substantially no armature current whenthe source to control. the load on the booster responsive to departuresfrom a predetermined electrical condition of the booster, said meansincluding a motor device connected to receive no energy when the batteryis floating, but arranged to become active as the booster becomesactive.

20. In an electrical system of distribution, a source of electricenergy, a feed circuit and its load supplied thereby, a storage batteryand a booster connected in a circuit across the feed circuit, and meansfor controlling the division of load on the system responsive tofluctuations thereof, said means including a motor device having itsarmature and field current responsive to changes in the electricalcondition of the booster.

21. In an electrical system of distribution, a source of electriccurrent, a feed circuit and its load supplied thereby, a battery and itscircuit in operative relation thereto, a booster for controlling thebattery action, and means for varying the potential of said source tocontrol the load on the booster responsive to departures from apredetermined electrical condition of the booster, said means includinga motor connected to receive substantially no energy when the booster isinactive.

22. In an electrical system of distribution, a source of electricalcurrent, a feed circuit and its load supplied thereby, a battery and itscircuit in operative relation thereto, a booster for controlling thebattery action, and means for varying the potential of said source tocontrol the load on the booster responsive to departures from apredetermined electrical condition of the booster, said means includinga plurality of motor devices each having its armature connected to besupplied from a source of electro-motive-force which varies responsiveto fluctuations of the voltage across the booster, one of said deviceshaving a field coil responsive to booster voltage and the other of saiddevices having a field coil responsive to booster current.

23. In combination, a circuit to be regulated, a variable resistance forregulating said circuit, a movable member for controlling saidresistance, *two motor devices for operating said movable member, eachdevice being provided with a regulating field coil and a field coilhaving a substantially constant exciting effect.

2%. In combination, a circuit to be regulated, a variable resistance forregulating said circuit, a movable member for controlling saidresistance, two motor devices for operating said movable member, eachdevice being provided with field and armature windings arranged to causesaid devices to rotate in either direction, and means for causing theefiect of said windings to be difierent when the rotation is in onedirection from the effect of said windings when the rotation is in theopposite direction.

25. In combination, a circuit to be regulated, a variable resistance forregulating the same, a movable member for controlling said resistance, aplurality of dynamometers for operating upon-said movable member, acircuit means for producing variable direct currents in both directionsin said circuit, means for energizing said dynamometers so that theywill operate in both directions responsive to departures from apredetermined electrical condition of said last mentioned circuit andmeans for causing the effect of said dynamometers-to be different whenthe current in said last mentioned circuit is in one direction from theeffect of said dynamometers when the current in said last mentionedcircuit is in the opposite direction.

In testimony whereof, I have signed my name to this specification, inthe presence of two subscribing witnesses.

ALBERT S. HUBBARD.

Witnesses:

EDWIN SEGER, GoRHAM CROSBY.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. G.

